One contained the late Robin Williams's Mork, just arrived from planet Ork in silver boots, matching gloves and jumpsuit – he looked not so much cosmic refugee as reject from a Glitter Band audition. Mork had been dispatched to Earth ostensibly to get the poop on the denizens of this backward planet, but really because his Orkan overlords (the peculiarly named Orson especially) wanted to get rid of this little twerp who kept making jokes contrary to the Orkan prohibition on humour. Man, those Orkans – they make Vulcans seem like a laugh riot.

And the second egg? That contained Mork's suitcase. He was going to be on our planet for some time.

Originally broadcast on ABC between 1978–82, Mork & Mindy typified a shift in popular culture. In the 50s, US sci-fi allegorised the red scare, projecting on to the tin-foiled alien Other the Americans' fears of Moscow. Much late-70s sci-fi, by contrast, consisted of American self-criticism. That's why much of Mork & Mindy's comedy came from Mork's end-of-show reports to Orson, in which he explained what he had learned about human customs, reproductive practices and electrical appliances. Orson couldn't believe what he heard and reproved his junior thus: "Have you been smoking your socks again, Mork?"

Strikingly, Mork first appeared on TV in an episode of Happy Days, a 70s TV show that nostalgically recalled that 50s America of cold war and hot rock'n'roll. For reasons too complicated to get into right now, Mork had a contest with Happy Days' cool ruler, the Fonz, culminating in him battling using Orkan finger against Fonzian thumb. Counterintuitively, this vignette proved so funny that ABC commissioned a spin-off entitled Mork & Mindy.

Once Mork had emerged from his egg spacecraft and retrieved his luggage, he met Mindy, the sweet 21-year-old played by Pam Dawber (destined over 91 episodes to be straight foil to Williams's slapstick schtick and often pre-verbal jibbering). She'd just been abandoned by her boyfriend and so needed to be chaperoned back to town. By then, Mork had changed out of his alien duds and into Earthling civvies so he could fit in. Only one problem: he was wearing his suit and tie back to front. That's why Mindy trusted him: Mork's collar made him look like a priest. At the time, trusting a man who looked like a priest may have seemed sensible – Mork & Mindy took place, after all, a long time ago in a TV galaxy far, far away.

All this may sound lame to younger readers, but if you spent, as I did, most of the 70s in school playgrounds making sure Oxford bags fell just so over stack-heeled soles, you needed to know your Mork & Mindy. If you didn't twiddle both ears while greeting playmates with Mork's "Nanu Nanu", or curse adversity by exclaiming "Shazbot!", you were, truly, a social pariah.

Time travelling back to this strange era in TV history after nearly 40 years and Robin Williams's desperately sad death is a bittersweet pleasure. The canned laughter echoes hollowly across spacetime. Mork's sartorial moves (braces over a stripy top? That padded jacket with rainbow motif? The strides that were all waistband and too little in the leg?) don't wear well. But watching series one with my eight-year-old daughter revived happy memories of daft gags involving alien faux pas. The phone rings and Mork answers the toaster? They don't write them like that any more …

By the second series, though, ABC had licensed all kinds of ill-advised silliness. In one episode, Raquel Welch, as a sashaying Necroton alien called Captain Nirvana, came to Earth to suck out Mork's brain and destroy the blue planet. She was flanked by two no-less-pneumatic flunkies called Kama and Sutra in silver bikinis who, for reasons that need not detain us, pawed our hero in a hot tub while he sported only singlet and jockeys.

ABC's mistake was that it kept throwing bad ideas at the problem. The problem being that we viewers didn't care about the minor characters: all we wanted was for Williams to get his alien freak on. It was a one-man show in all but name, so whatever ABC did with the supporting cast (such as disappearing with Pinochetian ruthlessness Fred and Cora from the music store where Mindy worked and replacing them with younger, even less interesting characters at a New York-style deli at the end of season one) did nothing to stop the show's ratings plummet. As for Williams, the show became a ladder that once ascended could be kicked away in his rise into the entertainment stratosphere.

The fourth and final series, in which Mork and Mindy get married and have a child who, according to Orkan developmental principles, ages backwards, is something that I can only now watch with a rictus of horror. But let's not remember Mork & Mindy that way. Let's remember it at its daft, innocent, season one best. Once Mindy found Mork busy at the breakfast table. "Mork, why are you building a tower of Cheerios?" "Because it's hard to stack oatmeal." It's funny because it's true. And because it's silly.